1. Field of the Invention
The invention relates to the field of video recorder systems and, more specifically, systems and methods for recording, indexing, and navigating video content.
2. Description of the Related Art
Video recorder technology, such as videocassette recorders (VCRs) and digital video recorders (DVRs), have increased consumer control over how and when consumers view video programming. Since the advent of VCRs, consumers have been able to record broadcast video (e.g., television, cable, and satellite broadcasts) for later viewing. A video program is recorded onto a storage medium, such as a videocassette. The users can then view the program from the videocassette at their leisure. VCRs also provide navigation features for viewing the stored programs. VCRs typically allow users to pause, fast forward, and rewind through portions of the program, with or without viewing them. Some VCRs offer added navigational features, such as slow motion and variable speed fast forward and rewind, though the quality of these features is limited by the analog technology involved. Consumers viewing a recorded program can use the fast forward feature to advance quickly through content that they do not wish to view. A common use of this feature has become skipping commercials in recorded programs.
Recognizing that consumers desire the ability to quickly and accurately avoid the commercials in recorded programs, a feature was developed for VCRs that automated the identification and skipping of commercials. These VCRs use analog or digital video processing to identify events in the video signal that typically mark advertisements. Some of the events commonly identified include: black fields (the frames of “blank” video that are inserted between commercials), silent fields (the “blank” audio that frequently accompanies black fields), and abrupt volume changes (the volume increases that frequently accompany commercials). Unfortunately, these events may sometimes occur in program content, as well as in and around commercials.
Commercials are almost invariably presented in commercial groups that follow definable patterns. Black field and silent field events may separate each commercial in a commercial group. In order to overcome the limitations of identifying commercials based upon an isolated event, pattern-matching logic is used by the VCRs to identify the event patterns in commercial groups. Identified events are temporarily saved to buffer. A series of events in the buffer are analyzed according to the spaces between them. If a predefined pattern is recognized, a commercial group is identified. Once a commercial group is identified, appropriate markers are recorded on the videocassette, usually written into the control track. During playback, the beginning marker initiates automatic fast-forwarding. The fast-forwarding continues until an end marker for the group is reached. At which time, the VCR returns to normal play mode. The advertisement skipping logic may also provide a video display, such as a blue screen, during the automatic fast-forwarding.
Commercial skipping VCRs have a number of shortcomings that reduce their usability and effectiveness. First, events may not be as simple to reliably detect as they first appear. Signal quality can radically impact the quality of black fields and silence fields. The signal is rarely, if ever, actually zero. Additionally, many television networks and content providers have implemented watermarking or logos that appear even on black field screens. Delivery systems, networks, and content providers can all impact the quality of the black fields and silence. There are other variations in the types of frames used to separate advertisements and program content, such as full screen logos and monochrome screens other than black. The variety and complexity of events is likely only to increase in a digital broadcast environment and may include proactive attempts by networks and advertisers to evade commercial detection. Improved methods of detecting events, such as black fields and silent fields, are desirable.
Similarly, there is a great variation in the event patterns that may be used to identify commercial groups. Confusion with the scene pacing in a program may lead to false identification of commercial groups or portions of commercial groups, causing program content to be automatically skipped. In current implementations, commercial skipping logic does not even attempt to identify commercial groups near the beginning or ending of a program, where credits, teasers, and previews make it difficult to separate advertisements from program content. Event patterns may vary across networks, programs, and the time of day, week, or year. Event patterns may also evolve over time based upon changes in advertiser and viewer preferences. Event patterns are particularly susceptible to variation by the broadcast providers in order to avoid the pattern recognition logic of current systems. Improved methods of updating and executing pattern recognition logic are desirable.
Commercial skipping VCRs do not identify and mark commercials during initial recording, or even during first playback. The pattern matching function requires the buffering of multiple events before an earlier event can be identified as signifying the beginning of a commercial group. Further, the markers identifying the starting and ending points of the commercial group are stored on the videocassette. Once a commercial group is identified, the arrangement of reading and writing heads in most VCRs requires that the tape be rewound to the start of the commercial group in order to record the start marker on the videocassette. After initial recording but before the recording can be viewed with the commercial skipping feature, most commercial skipping VCRs execute a separate pass through the videocassette to identify events, identify commercial groups, and mark the commercial groups on the videocassette. Improved methods of indexing stored commercial groups are desirable.
Commercial skipping VCRs provide limited navigation options for identified commercials and commercial groups. Sequential recording and playback limit the practical options for navigating video content stored on videocassettes. The only navigation option provided by most commercial skipping VCRs is to skip identified commercial content based upon the beginning and ending markers placed in the control track. This function is generally binary—it is either on or off. However, users may desire more control over how and when commercial groups, or other identified video content, are viewed or not viewed. Improved methods of navigating indexed commercial groups are desirable.
DVRs are revolutionizing the way broadcast video content is stored, managed, and viewed. DVRs include systems for receiving, digitally storing, and playing back video content, such as video programs and commercials. DVRs generally use a digital storage media, such as a hard drive, for digitally storing compressed video content. While the video content is stored digitally, it is often received and played back as an analog signal-requiring one or more analog/digital converters. DVRs may provide a large number of enhancements for receiving, storing, and viewing video content, such as interactive program guides, interactive management of stored content, automated recording of new content, enhanced navigation features, file sharing and communications features, and other enhancements. Many of these enhanced features involve substantial data processing, memory, network, and graphical interface overlay capabilities. The combination of more flexible storage systems (e.g., digital file systems), enhanced processing power, and ubiquitous network technologies provides great potential for DVRs to overcome many of the limitations of VCRs.
Most DVRs store video content as compressed video files using a digital compression standard, such as MPEG. In order to provide time-based access to and navigation of the video files, DVRs may generate a companion index file containing a time index of the video file. For example, the index file may correlate GOPs (Group of Pictures, a unit of MPEG compressed data) to elapsed time. DVRs may use the data from the index file to enable time-based manipulation of the video data stream during play back. Varying the progression followed through the index file enables enhanced navigation options, such as slow motion, fast-forwarding, and rewinding—all at variable speeds and with better fidelity than prior analog systems. The index file frees the system from sequential access to the content file by allowing the system to directly access any time point in the content file. This aspect of the index file has been used to provide instant replay and skip forward features. These features provide a predefined jump backwards or forwards in the data stream during playback. They are commonly used to review content the user would like to see again or to skip content the user does not want to see at all. A favored use of the skip forward feature is to skip quickly through commercial groups. A 30 second skip forward is fairly effective in quickly navigating through commercials, which frequently run about 30 seconds or a multiple thereof. When used in this way, the user identifies the presence of a commercial and activates the skip forward, generally using a designated button on a remote control. If the user arrives at another commercial, the skip forward is activated again—and so on, until the user arrives at the desired program content. Hopefully, the skip forward does not carry the user too far, missing content the user wanted to see. While this method of avoiding commercials during playback has proven popular with DVR users, improved methods of detecting commercials and automatically skipping them are desirable.